Opioids and risk of type 2 diabetes in adults with non-cancer pain.

BACKGROUND While the use of opioids for chronic non-cancer pain (CNCP) has increased dramatically in the past 2 decades, concern exists about the safety of opioids, particularly with the extensive use among individuals with CNCP. OBJECTIVE To assess the risk of type 2 diabetes (T2D) among adults exposed to opioids for non-cancer pain. STUDY DESIGN Nested case-control study. SETTING United Kingdom-based General Practice Research Database (GPRD). METHODS Among 1.7 million opioid users with at least one prescription for an opioid to treat non-cancer pain in the GPRD (1990 - 2008), we identified all incident T2D cases with at least 2 years of medical history before their first diagnosis (index date). For each case we randomly selected up to 2 controls matched on age, gender, index date, and general practice. The same eligibility requirements were applied to controls as to cases. We defined "any exposure" as at least 2 prescriptions for an opioid within 2 years before the index date and defined "nonuse" as no use or only one prescription within 2 years (reference). For any exposure to opioids we further evaluated timing of use, cumulative use, and individual opioid type. Conditional logistic regression was used to estimate adjusted odds ratios (AORs) and 95% confidence intervals (CIs) controlling for confounders. RESULTS We identified 50,468 T2D cases to which we matched 100,415 controls. Cases were more likely than controls to be former smokers, heavier, and to have more co-morbidities, co-medications, and visits to their general practitioners. After adjusting for important confounders there was no increased risk for T2D among those exposed to any opioid compared to nonusers (AOR = 1.03, 95% CI 1.00 - 1.06). The results did not change when we evaluated timing of use, cumulative use, or individual opioid type. LIMITATIONS Misclassification of exposure may have occurred; limited data for some individual opioid types. CONCLUSION This study found no association between use of opioids and risk of T2D among non-cancer adults.